Hash private RFQ fields

[diehuxx]

Add privateData to RFQ and make exceptions more precise and easier to catch. From the dart docs for the Exception class,

Creating instances of Exception directly with Exception("message") is discouraged in library code since it doesn't give users a precise type they can catch. It may be reasonable to use instances of this class in tests or during development.

The pattern of "error codes" is borrowed from dwn-sdk-js. The pattern of custom error classes -- TbdexParseException, TbdexValidatorException, etc. -- makes it easier to catch specific exceptions from an action like .parse() or .validate().

[diehuxx]

Not every code is tested as of this PR. In subsequent PRs, we can flesh out tests to cover more cases.

[kirahsapong]

In tbdex-js we only use this functionality in the server, so swift doesn't implement anything that isn't consumed by the client, and scopes anything needed for testing to the test files. Do you want to follow the same pattern here?

My suggestion is to:

• omit parse, verifyAllPrivateData and verifyPresentPrivateData as these are not consumed by a client
• collapse verifyPayinDetailsHash, verifyPayoutDetailsHash, and verifyClaimsHash into a verifyHash that accepts args
• scope verifyHash to tests

[diehuxx]

I'd prefer to keep the requireAllPrivateData functionality. My understanding for tbdex-swift was that we omitted that functionality because we were up against a deadline and omitting it from swift was a good trade off to cut down on eng work.

Since I've already paid the upfront cost of implementing this is dart, I don't see any drawback to keeping it in. Even though we won't necessarily use that functionality for didpay, other package consumers might find it useful for their dart apps. E.g. someone writes p2p tbdex client in dart that has both pfi and wallet functionality.

[kirahsapong]

My understanding for tbdex-swift was that we omitted that functionality because we were up against a deadline and omitting it from swift was a good trade off to cut down on eng work.

cool thanks for clarifying @diehuxx

@frankhinek @angiejones can you confirm? thats not what my understanding was and it would be ideal to align sdks semantically. if we are adding pfi functionality broadly including in swift i'd like to create issues asap.

[ethanwlee]

should we throw a TbdexParseException here?

[diehuxx]

woops, we definitely should. fixed

[ethanwlee]

thanks for getting to this!!